Method and apparatus for processing a downlink shared channel

ABSTRACT

A method and apparatus for receiving a wireless signal of a control channel wherein the wireless signal includes control information and an N bit field. The N bit field includes an N bit cyclic redundancy check (CRC) and an N bit user equipment (UE) identity wherein the value of N is a positive integer. The UE identity may be any one of a plurality of UE identities associated with the UE.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.11/129,850, filed May 16, 2005, which issued as U.S, Pat. No. 7,783,953on Aug. 24, 2010, which is a continuation of U.S. patent applicationSer. No. 10/035,771, filed Dec. 26, 2001, which issued as U.S. Pat. No.6,915,473 on Jul. 5, 2005, which claims the benefit of U.S. ProvisionalApplication Nos. 60/290,740, filed May 14, 2001; 60/314,993, filed Aug.24, 2001; and 60/345,358, filed Oct. 25, 2001, which are incorporated byreference as if fully set forth herein.

BACKGROUND

The present invention relates to the field of wireless communications.One of the applications of the present invention is directed to adownlink signaling approach employing a modified cyclic redundancy checkfor both data protection and unique/group UE identification.

Wireless communication systems have become an integral link in today'smodern telecommunications infrastructure. As such, they have becomeincreasingly relied upon not only to support voice communications, butalso data communications. Voice communications are relatively low-rate,symmetrical in the upstream and downstream bandwidths and arepredictable in the amount of bandwidth required.

However, data communications can place severe burdens upon atelecommunication system, particularly a wireless telecommunicationsystem. First, data communications can often require extremely high datarates. Second, the amount of bandwidth for a data related applicationcan vary greatly from several kilohertz of bandwidth to severalmegahertz. Third, the amount of bandwidth in the upstream and downstreamdirections can be drastically different. For example, with a typicalInternet browsing application, very little data is sent in the upstreamdirection while vast amounts of data are downloaded in the downstreamdirection. These factors can place severe constraints upon a wirelesstelecommunication system.

The Wideband CDMA (WCDMA) standard, as the leading global thirdgeneration (3G) (IMT-2000) standard, supports data rates up to 2 Mb/s inindoor/small-cell-outdoor environments and up to 384 kb/switch wide-areacoverage, as well as support for both high-rate packet data andhigh-rate circuit-switched data. However to satisfy the future demandsfor packet-data services, there is a need for a substantial increase inthis data rate, especially in the downlink. High speed downlink packetaccess (HSDPA) would allow WCDMA to support downlink peak data rates inthe range of approximately 8-10 Mb/s for best-effort packet-dataservices. This rate is far beyond the IMT-2000 requirement of 2 Mb/s. Italso enhances the packet-data capability in terms of lower delay andimproved capacity.

One solution for supporting data communications is the allocation ofdedicated channels to each user equipment (UE). However, this results inan extremely inefficient use of the bandwidth since such channels oftenremain idle for long durations.

An alternative to dedicated channels for each UE is the use of the highspeed shared data channels and the packeting of data. In this method, aplurality of high speed data channels are shared between a plurality ofUEs. Those UEs having data for transmission or reception are dynamicallyassigned one of the shared data channels. This results in a much moreefficient use of the spectrum.

One such process for assigning a high speed shared data channel when abase station has data waiting for transmission to a particular UE isshown in FIGS. 1A-1C. Referring to FIG. 1A, an associated downlinkdedicated physical channel (DPCH) is transmitted to each UE. The UEmonitors associated downlink DPCH as well as the shared control channels(SCCH-HS). When there is no data being transmitted to the UE from thebase station, the UE enters a standby mode whereby it periodically“wakes up” to attempt to monitor its associated downlink DPCH as well asSCCH-HSs. This permits the UE to save processing and battery resources.

If data at the base station is ready for transmission to the UE, a HighSpeed Downlink Shared Channel (HS-DSCH) indicator (HI) is transmitted inthe associated DPCH. The HI has n-bit length, which points to one of2^(n) SCCH-HSs shown in FIG. 1B. For example a 2 bit HI can point to 4SCCH-HSs, i.e., 00, 01, 10 or 11.

For the example shown in FIG. 1A, the HI is (1, 0) which points to thethird channel shown in FIG. 1B. When the UE accesses the control channelidentified by the HI, that particular SCCH-HS will direct the UE to theproper HS-DSCH, which has been allocated to the UE for reception of thedata. As shown in FIG. 1C, for example, the UE tunes to HS-DSCH (001)that was identified by SCCH-HS (1, 0). The UE then receives the dataintended for it over the HS-DSCH (001). It should be noted that thegraphical representation of FIG. 1A-1C has been presented to illustratethe process of assigning HS-DSCHs, and the configuration and use ofchannels may differ slightly from actual implementation in HSDPAstandards.

The process as described with reference to FIGS. 1A-1C provides anefficient method for assigning common data channels for transmission ofdata. Since packet data is intended for one or more, specific UEs, theUE identity (ID) is a critical parameter for signaling from the basestation to the UE.

There are several prior art methods for signaling the UE ID between thebase station and the UE. Referring to FIG. 2A, the first method appendsthe UE ID onto the data for transmission. The combination is fed to acyclic redundancy check (CRC) generator, which outputs a CRC. Theresulting data packet, which is ultimately transmitted, includes anX-bit data field, an M-bit UE ID and an N-bit CRC as shown in FIG. 2B.Although this provides adequate signaling of both the CRC and the UE ID,it is wasteful of signaling bandwidth.

Another prior art technique shown in FIG. 3A appends the UE ID onto thedata field for input into the CRC generator. The CRC generator outputs aCRC. As shown in FIG. 3B, the data burst for transmission includes anX-bit data field and an N-bit CRC field. Although this also adequatelysignals the UE ID and the CRC between the base station and the UE, it isundesirable since it can only be used for unique UE identification. Thismethod also causes increased complexity of the UE when a group of UEsneed to be identified.

SUMMARY

A method and apparatus is disclosed wherein a user equipment (UE)receives control information on a first channel and uses the controlinformation to process a second channel.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1C represent a prior art method for assigning shared datachannels, where FIG. 1A illustrates the associated downlink channel,FIG. 1B illustrates a plurality of control channels and FIG. 1Cillustrates a plurality of data channels.

FIG. 1D is a block diagram of the universal mobile telecommunicationsystem network architecture.

FIG. 2A is a prior art user equipment identification (UE ID) specificcyclic redundancy check (CRC) method.

FIG. 2B illustrates the transmitted data burst including a data field, aUE ID field and a CRC field.

FIG. 3A is a second prior art user equipment identification (UE ID)specific cyclic redundancy check (CRC) method.

FIG. 3B illustrates the transmitted data burst including a data fieldand a CRC field.

FIG. 4A is a first embodiment of the present invention utilizing modulo2 addition of the UE ID with the CRC to create a mask.

FIG. 4B is a data burst transmitted by the system of FIG. 4A including adata field and a mask field.

FIG. 5A is a second embodiment of the present invention including a CRCgenerator which is initialized using the UE ID.

FIG. 5B is a data burst transmitted by the embodiment of FIG. 5Aincluding a data field and a CRC field.

FIG. 6A is a third embodiment of the present invention which modulo 2adds the data field to a UE ID field padded with trailing zeros tocreate a mask.

FIG. 6B is a fourth embodiment of the present invention which modulo 2adds the data field to a UE ID field padded with leading zeros to createa mask.

FIG. 6C is the data burst transmitted by the embodiments of FIG. 6A and6B including a data field and a CRC field.

FIG. 7A is a fifth embodiment of the present invention which modulo 2adds the data field to a UE ID field repeated and padded a truncated UEID in the trailing bits.

FIG. 7B is a sixth embodiment of the present invention which modulo 2adds the data field to a UE ID field repeated and padded a truncated UEID in the leading bits.

FIG. 7C is the data burst transmitted by the embodiments of FIG. 7A and7B including a data field and a CRC field.

FIG. 8 is a tabulation of global, subset, subsubset and unique IDs.

FIG. 9 is a flow diagram of the processing of a message in accordancewith the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The presently preferred embodiments are described below with referenceto the drawing figures wherein like numerals represent like elementsthroughout.

Referring to FIG. 1D, a Universal Mobile Telecommunications System(UMTS) network architecture used by the present invention includes acore network (CN), a UMTS Terrestrial Radio Access Network (UTRAN), anda User Equipment (UE). The two general interfaces are the Iu interface,between the UTRAN and the core network, as well as the radio interfaceUu, between the UTRAN and the UE. The UTRAN consists of several RadioNetwork Subsystems (RNS). They can be interconnected by the Iurinterface. This interconnection allows core network independentprocedures between different RNSs. The RNS is further divided into theRadio Network Controller (RNC) and several base stations (Node-B). TheNode-Bs are connected to the RNC by the Iub interface. One Node-B canserve one or multiple cells, and typically serves a plurality of UEs.The UTRAN supports both FDD mode and TDD mode on the radio interface.For both modes, the same network architecture and the same protocols areused. Only the physical layer and the air interface Uu are specifiedseparately.

Referring to FIG. 4A, one embodiment of the present invention is shown.In this embodiment, the system 100 utilizes the data for transmission(hereinafter referred to as “data”) from the data field 102, a CRCgenerator 104 (which has been initialized to zero), the resulting CRCfrom the CRC field 106 output from the CRC generator 104, the UE ID fromthe UE ID field 108, a modulo 2 adder 110 and a mask 112. It should benoted that in this embodiment and all of the embodiments describedhereinafter, the number of bits of each field is noted above the fieldas an example. However, the specific number of bits is exemplary andshould not be construed to limit the present invention.

The system 100 receives the data field 102 and inputs the data from thedata field 102 into the CRC generator 104. The CRC generator 104generates the CRC field 106 and outputs the CRC from the CRC field 106to a first input of the modulo 2 adder 110. The UE ID from the UE IDfield 108 is output to the second input to the modulo 2 adder 110. TheCRC and UE ID are then modulo 2 added to create a mask 112.

Preferably, the number of bits of the UE ID field 108 (M bits) is thesame as the number of bits of the CRC field 106 (N bits). If M=N, thenthe UE ID may be directly modulo 2 added to the CRC as shown in FIG. 4A.However, if M and N are not equal, then an interim step is necessary tomake them equal. If M<N, then the UE ID is padded with either leadingzeros or trailing zeros to be equal in length to the CRC. This “paddedUE ID” is N modulo 2 added to the CRC 106. If M>N, then the leastsignificant M-N bits are truncated from the UE ID. The truncated UE IDis then modulo 2 added to the CRC.

Referring to FIG. 4B, the mask 112 that is generated is appended to thedata field 102 for transmission.

Referring to FIG. 5A, a second embodiment of the present invention isshown. In this embodiment, the system 200 utilizes the data from thedata field 202, a CRC generator 204, the UE ID from the UE ID field 208,and the resulting CRC field 212. The system 200 receives the data field202 and outputs the data from data field 202 into the CRC generator 204.The CRC generator 204 is the same type of generator as the CRC generator104 from FIG. 4A, except that the CRC generator 204 is initialized withthe UE ID from the UE ID field 208. This initialization is illustratedby the dotted line in FIG. 5A. As is well known by those of skill in theart, a CRC generator is typically initialized to all zeros, as was thecase with the CRC generator 104 shown in FIG. 4A. Accordingly, the CRCgenerator 204 generates a CRC based upon the input data from the datafield 202 and the initialization of the CRC generator 204 with UE ID. Nomodulo 2 addition is required in this embodiment.

Preferably, the number of bits of the UE ID from the UE ID field 208 (Mbits) is the same as the size of the CRC generator 204, although this isnot necessary. If the size of the UE ID (M-bits) is less than the sizeof the CRC generator 204, then the UE ID may be padded with eitherleading zeros or trailing zeros to be equal in length to the size of theCRC generator 204. This “padded UE ID” may then be used to initializethe CRC generator 204. Alternatively, the value in the UE ID field 208may be loaded to initialize the CRC generator 204, and any bit positionsnot filled by the UE ID would be zero. If the size of the UE ID (M bits)is greater than the size of the CRC generator 204, then the leastsignificant bits are truncated from the UE ID in order to fit the UE IDto CRC generator 204. The truncated UE ID is then used to initialize theCRC generator 204.

Referring to FIG. 5B, the CRC field 212 that is generated is appended tothe data field 202 for transmission.

This second embodiment of the present invention utilizing implicit UE IDpresents a simplistic, yet robust, alternative since it does not requireassembly and disassembly of the UE ID with the SCCH-HS, at thetransmitter or the receiver, as required by UE-specific CRC methods ofthe prior art and the first embodiment.

Referring to FIG. 7A, a fifth embodiment of the present invention isshown. In this embodiment, the system 400 utilizes the data from thedata field 402, the UE ID from the UE ID field 408A, a modulo 2 adder410, a mask 411, a CRC generator 404 and the resulting CRC field 412.The system 400 receives the data field 402 and inputs the data from thedata field 402 into a first input of the modulo 2 adder 410. The UE IDfrom UE ID field 408A is output to the second input to the modulo 2adder 410. The data from the data field 402 and the UE ID from the UE IDfield 408A are modulo 2 added to create a mask 411. The mask 411 isinput into the CRC generator 404, which generates the CRC field 412.

In this embodiment, the number of bits of the UE ID field 408A (M bits)must be the same as the number of bits of the data field 402 in order toperform the modulo 2 addition. If the M is equal to X, then the UE IDfrom the UE ID field 408A may be directly modulo 2 added to the datafrom the data field 402. Due to the length of the data field 402, it isnot expected that M will be greater than X. However, if this were tooccur, then the least significant bits are truncated from the UE IDfield 408A until the length of the UE ID field is equal to X. Thetruncated UE ID is then modulo 2 added to the value from the data field402.

Due to the length X of the data field 302, it is not expected that Mwill be greater than X. However, if this were to occur, then the leastsignificant M-X bits are truncated from the value in UE ID field 308A.The truncated UE ID is then modulo 2 added to the data from the datafield 302.

Referring to FIG. 6B, a fourth embodiment of the present invention isshown. In this embodiment, the system 301 operates in the exact samemanner as the third embodiment shown in FIG. 6A. The only difference inthis embodiment is the method in which the value from the UE ID field308B is generated. In this embodiment, the UE ID is padded with X-Mleading zeros such that the UE ID from the UE ID field 308B is equal inlength to the data field 302. This “padded UE ID value”, as shown inFIG. 6B, is then modulo 2 added to the data from the data field 302. Itshould be noted that the padding may alternatively comprise acombination of leading and trailing zeros (not shown) in order to makethe UE ID the same length as the data field.

Referring to FIG. 6C, the CRC field 312 that is generated from thesystem 300 of the third embodiment shown in FIG. 6A, or the CRC 314 thatis generated from the system 301 of the fourth embodiment shown in FIG.6B, is appended to the data field 302 for transmission. Accordingly,either type of CRC field 312, 314 may be used and appended onto the datafield 302.

Referring to FIG. 7A, a fifth embodiment of the present invention isshown. In this embodiment, the system 400 utilizes the data from thedata field 402, the UE ID from the UE ID field 408A, a modulo 2 adder410, a mask 411, a CRC generator 404 and the resulting CRC field 412.The system 400 receives the data field 402 and inputs the data from thedata field 302 into a first input of the modulo 2 adder 410. The UE IDfrom UE ID field 408A is output to the second input to the modulo 2adder 410. The data from the data field 402 and the UE ID from the UE IDfield 408A are modulo 2 added to create a mask 411. The mask 411 isinput into the CRC generator 404, which generates the CRC field 412.

In this embodiment, the number of bits of the UE ID field 408A (M bits)must be the same as the number of bits of the data field 402 in order toperform the modulo 2 addition. If the M is equal to X, then the UE IDfrom the UE ID field 408A may be directly modulo 2 added to the datafrom the data field 402. Due to the length of the data field 302, it isnot expected that M will be greater than X. However, if this were tooccur, then the least significant bits are truncated from the UE IDfield 408A until the length of the UE ID field is equal to X. Thetruncated UE ID is then modulo 2 added to the value from the data field402.

If the length of the UE ID is shorter than the data field 402, then a“composite UE ID” is created such that the value from the UE ID field408A is equal to X. The composite UE ID is created by repeating the UEID as many times as it will fit within an X-bit field, then filling inthe remaining trailing bits with a truncated UE ID. This is representedin the UE ID field 408A in FIG. 7A. The composite UE ID is then modulo 2added to the data from the data field 402.

Referring to FIG. 7B, a sixth embodiment of the present invention isshown. The system 401 of this embodiment operates in the same manner asthe fifth embodiment shown in FIG. 7A. The only difference in thisembodiment is the value from the UE ID field 408B. Although thecomposite UE ID created in the same manner as in FIG. 7A, the truncatedUE ID portion is added as leading bits, as opposed to the trailing bitsin the UE ID field 408A shown in FIG. 7A. It should be noted that thetruncated UE ID “padding” may include a combination of leading andtrailing truncated bits in order to make the UE ID the same length asthe data field 402.

Referring to FIG. 7C, the CRC field 412 that is generated from eitherthe system 400 of the fifth embodiment shown in FIG. 7A, or the CRCfield 414 that is generated from the system 401 of the sixth embodimentshown in FIG. 7B, is appended to the data field 402 for transmission.Accordingly, either type of CRC field 412, 414 may be used and appendedonto the data field 402.

It should be noted that all of the above-described embodiments can beused to support multiple identities (IDs). A UE may be required toprocess messages addressed at several levels: 1) the UE's unique ID, 2)an ID corresponding to a subset or group of UEs, where the UE belongs tothe subset; or 3) a broadcast (global ID) corresponding to all UEs inthe system. For example, as shown in FIG. 8, UE ID 12 has beenhighlighted to indicate that it will able to receive and process IDs atfour different levels: 1) the UE-specific ID (#12); 2) subsubset C ID;3) subset 2 ID; and 4) global ID. It should also be noted that alternategroup identifications A-E, may also be created such that a differentgroup of UEs may be included. For example, group B will include all ofthe UEs identified next to group B which include UE numbers 2, 7, 12,17, 22 and 27. Additionally, any group or subgroup may be created byspecifically identifying individual UEs as desired by a user.

To support this requirement, the transmitter generates the CRC asdescribed above with each of the embodiments. At the receiver, the UEprocesses the message and generates the expected CRC, without theID-based modification. The UE processor then modulo 2 adds the receivedCRC to the calculated CRC. The resultant output is the transmitted ID,which can be any one of the IDs described above. If the ID is none ofthese, then the UE discards the transmission.

In accordance with the present invention, using the CRC code of thelength N, the undetected error probability on the identified SCCH-HSapproaches 2^(−n). Using a 24-bit CRC to protect data transmitted onHS-DSCH, a 16-bit CRC to protect control information transmitted onSCCH-HS, and assuming 10⁻³ false acceptance probability for HI bits byan unintended UE, the embodiments in accordance with the presentinvention hereinbefore described will provide the probability of thefalse acceptances as follows:P _(fa) =P _(fa) HI×P _(fa) H×P _(SD)   Equation (1)where P_(fa) is the probability of a false acceptance; P_(fa)HI is theprobability of a false acceptance of HI; P_(fa)H is the probability of afalse acceptance of SCCH-HS; and P_(SD) is the probability of asuccessful detection of HS-DSCH (P_(SD)).

Using the above identified values for the present example with Equation(1):P _(fa)=10⁻³×2⁻¹⁶×2⁻²⁴=9.1×10⁻¹⁶

The reliability computation indicates that for the same length CRC, theprobability of a user passing erroneous data up to a higher layer, willbe extremely low.

Referring to FIG. 9, the flow diagram illustrates a method forprocessing downlink messages between a node B and a UE in accordancewith the present invention. This method provides a general overview andshould not be interpreted as a comprehensive description of all of thedetailed medium access control (MAC) layer and physical layer signalingrequired for processing a message, (i.e., a data packet). The node Bfirst generates a downlink control message in the MAC layer (step 1) andthen forwards the message and the UE ID to the physical layer (step 2).The physical layer generates the CRC and applies the UE ID forforwarding with the message (step 3) as a data burst. The message isthen transmitted from the node B to the UE (step 4). At the physicallayer, the UE ID and the CRC are checked to determine if they arecorrect (step 5). If so, the message is forwarded to the MAC layer (step6) which then further processes the message (step 7).

It should be noted that step 6 in FIG. 9 includes an additional signalbetween the physical layer and the MAC layer, which comprises a controlmessage that indicates the CRC/UE ID is valid. However, this is anoptional step. In the preferred embodiment, only valid messages will beforwarded from the physical layer to the MAC layer. Accordingly, in thepreferred embodiment, the MAC layer will assume that any message that isforwarded to the MAC is valid. In the alternative embodiment, theadditional CRC/UE ID valid signaling will be forwarded along with themessage as an additional confirmation.

The present invention has the advantage of eliminating separateprocessing steps for the UE ID and the CRC. When the two fields arecombined as hereinbefore described, the UE will not further process anymessage until both the CRC and the UE ID (or other type of ID shown inFIG. 8) are correct.

While the present invention has been described in terms of the preferredembodiment, other variations, which are within the scope of theinvention, as outlined in the claims below will be apparent to thoseskilled in the art.

1. A user equipment (UE) comprising: circuitry configured to receive awireless signal of a control channel, wherein the wireless signalcomprises an N bit field and control information, and the N bit fieldcomprises an N bit cyclic redundancy check (CRC) modulo two added to anN bit UE identity, wherein the value of N is a positive integer;circuitry configured to determine whether criteria are met, wherein thecriteria include the CRC is correct and the UE identity is any one of aplurality of UE identities associated with the UE; and circuitryconfigured to use the control information to process a downlink sharedchannel on a condition that the criteria are met.
 2. The UE of claim 1further comprising circuitry configured to monitor a plurality ofcontrol channels.
 3. The UE of claim 1 wherein at least one of theplurality of UE identities associated with the UE is unique to the UE.4. The UE of claim 1 wherein at least one of the plurality of UEidentities associated with the UE is an identity assigned to the UE. 5.The UE of claim 4 wherein the identity assigned to the UE is uniquewithin a subset of UEs operating in a wireless network.
 6. The UE ofclaim 1 wherein at least one of the plurality of UE identitiesassociated with the UE identifies a group of UEs belonging to aplurality of subsets of UEs operating in a wireless network.
 7. The UEof claim 1 wherein at least one of the plurality of UE identitiesassociated with the UE is a global identity which is the same for eachUE operating in a wireless network.
 8. The UE of claim 7 wherein the UEreceives a broadcast message associated with the global identity on thedownlink shared channel.
 9. The UE of claim 1 wherein at least one ofthe plurality of UE identities associated with the UE is furtherassociated with a group of UEs operating in a wireless network.
 10. TheUE of claim 9 wherein the at least one of the plurality of UE identitiesassociated with the UE is a global identity which is the same for eachUE operating in the wireless network.
 11. A method implemented in a userequipment (UE) device comprising: the UE device receiving a wirelesssignal of a control channel, wherein the wireless signal comprises an Nbit field and control information, and the N bit field comprises an Nbit cyclic redundancy check (CRC) modulo two added to an N bit UEidentity, wherein the value of N is a positive integer; the UE devicedetermining whether criteria are met, wherein the criteria includes theCRC is correct and the UE identity is any one of a plurality of UEidentities associated with the UE device; and the UE device using thecontrol information to process a downlink shared channel on a conditionthat the criteria are met.
 12. The method of claim 11 further comprisingthe UE device monitoring a plurality of control channels.
 13. The methodof claim 11 wherein at least one of the plurality of UE identitiesassociated with the UE device is unique to the UE.
 14. The method ofclaim 11 wherein at least one of the plurality of UE identitiesassociated with the UE device is an identity assigned to the UE.
 15. Themethod of claim 14 wherein the identity assigned to the UE device isunique within a subset of UE devices operating in a wireless network.16. The method of claim 11 wherein at least one of the plurality of UEidentities associated with the UE device identifies a group of UEdevices belonging to a plurality of subsets of UE devices operating in awireless network.
 17. The method of claim 11 wherein at least one of theplurality of UE identities associated with the UE device is a globalidentity which is the same for each UE device operating in a wirelessnetwork.
 18. The method of claim 17 wherein the UE device receives abroadcast message associated with the global identity on the downlinkshared channel.
 19. The method of claim 11 wherein at least one of theplurality of UE identities associated with the UE device is furtherassociated with a group of UE devices operating in a wireless network.20. The method of claim 19 wherein the at least one of the plurality ofUE identities associated with the UE device is a global identity whichis the same for each UE device operating in a wireless network.